I'll catch you on the download!
The Tuning Fork of Harmony is a monument located on Musa's home realm of Melody. It is featured exclusively within the Winx Club Comic Series where its only appearance is in Issue 119: The Power of Music.
According to Musa, the Tuning Fork of Harmony was erected in ancient times by the Sages of Melody. Since then, the frequency caused by the Tuning Fork's magical vibrations has kept in time with Melody, keeping the harmony and melody of the realm alive. Due to this, it had become the realm's source of balance and even a source of power for some of the life on Melody, which includes Musa.